Conventionally, a camera is mounted on a vehicle, and the camera shoots an image around the vehicle. Thus, a part of the image is retrieved, i.e., extracted or cut off, and the part of the image is displayed on a display. Thus, a passenger of the vehicle recognizes the image around the vehicle. This display system for shooting an image around the vehicle is disclosed in, for example, JP-A-2008-230476, which corresponds to US Patent Application Publication No. 2008-0231702.
In the above system, the part of the image, which is retrieved from the original image, is defined as an extracted image. A range of the extracted image in the original image is defined by local coordinate system, which are fixed to the vehicle. Specifically, the range in the original image corresponds to a predetermined part of the vehicle. Thus, the part of the original image is retrieved from the original image, and the part of the original image is displayed as a predetermined region defined by the local coordinate system fixed to the vehicle. Thus, when the camera is mounted on the vehicle, the position and the orientation of the camera are adjusted to be a predetermined position and a predetermined orientation. Under a condition that the camera is adjusted to be a predetermined position and a predetermined orientation with respect to the vehicle, when the display system for shooting and displaying the image around the vehicle is manufactured, retrieved region information showing a retrieved range of the original image, which is defined by display coordinate system fixed to the original image, is preliminary set.
However, the actual position and the actual orientation of the camera may be different from a predetermined position and a predetermined orientation. Since the predetermined retrieved range information is preliminary determined under a condition that the camera is adjusted to be a predetermined position and a predetermined orientation, when the part of the original image is retrieved from the original image according to the predetermined retrieved range information, the region defined by the local coordinate system, which is actually displayed as the retrieved image, may be different from the proper region to be displayed. Specifically, the actual display region may shift from the proper region.
To reduce the shift between the actual display region and the proper region, the vehicle is places to certain environment, which provides to arrange a marker such as a LED at a certain position. Then, the original image is shot by the camera of the system in the vehicle, and the mismatch between the actual display coordinate system of the marker in the shot image and the proper display coordinate system of the marker in the proper image is calculated. Based on the calculated mismatch, the actual display coordinate system is corrected to modify the actual retrieved range of the original image. However, in this case, it is necessary to place the vehicle in the certain environment. Thus, this modification can be performed before the vehicle is shipped.